Automobile tow bar with bumper clamp



March 16, 1954 A R, GROSS 2,672,353

AUTOMOBILE TOW BAR WITH BUMPER CLAMP Filed Jan. l1, 1951 2 Sheets-Sheet l Minimum@ March 16, 1954 A. R. GROSS AUTOMOBILE Tow BAR WITH BUMPER CLAMP 2 Sheets-Sheet 2 Filed Jan. l1, 1951 Patented Mar. 16, 1954 2,672,353' AUTOMOBILE TOW BAR WITH, BUMPER CLAMP Arthur It. Gross, St. Paul, Minn., assigner, .by mesne assignments, to Automatic lJIow Bar Company, Inc., Minneapolis, Minn., a corporation of Minnesota Application January 11, 1951, Serial No. 205,574

l 7 Claims This invention relates to an improved automobile tow bar of the type adapted to relatively quick installation and particularly suitable for towing automobiles relatively short distances, as in intra-city and intra-state areas.

A tow bar for use in towing automobiles for short distances is preferably characterized by quick and easy adjustment to the vehicles, strength and safety in its operation, and being adapted to facilitate guiding the towed vehicle through city tratlic. It is toward a tow bar having` these features that this invention is directed.

One of the objects of my invention is to provide a tow bar of simplified design which is adapted to quick and efficient installation and removal from the towing and towed vehicles.

Another object of my invention is the provision of a tow bar in which the individual parts are inexpensively fabricated, but which, when assembled, produce a unit of unusual strength and safety.

A further object of my invention is a tow bar which is yieldable to the independent motion of the vehicle, but which increases the control and response of the towed vehicle, particularly as to steering.

A more specic object of my invention is to provide a tow bar with a universal joint action having improved strength and safety character- -istics Further objects and advantages of the inven.. tion will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

In the drawings:

Fig. 1 is a side elevational View illustrating the installation and adaptation of a preferred embodiment of my invention as utilized for the towing of one automobile from another; l Fig. 2 is a vertical sectional view of the tow bar, drawn to a larger scale than Fig. 1, and depicting its attachment to automobile bumpers;

Fig. 3 is a plan view, partly in section, and viewed from a position indicated by line 3-3 of Fig. 2;

Fig. 4 is an exploded perspective View showing the component par-ts of the tow bar, shown in Figs. 1, 2 and 3; and

Fig. 5 is a perspective view similar to Fig. 4 showing the component parts of the tow bar in assembled relationship.

In the preferred embodiment of the invention, as illustrated in the drawings, a tow bar l comprises a forward bumper clamp H and a rear (Cl. 28o-505) bumper clamp i2y joined by connecting bar i3; The clamps ll and t2 are adapted to engage the bumpers of the towing and towed vehicles.; the bar i3, of course, furnishing the means. ofv towing the.- rear vehicle.

Each of the clamps H .and I2 comprise a pair of clamp jaws, those of the rear clamp being indicated at I4 and l5, and those of the forward clamp being indicated at 16 and il. The upper clamp jaws l5 and I1 are of flat plate stock formed into a substantially S-shape and provided with a chain slot 29, Fig. 4. Preferably, each of the lower clamp jaws 14 and i6 are of sturdier and more rigid construction than the upper jaws l5 and l1. This is because the lower jaws provide the towing' connections to the con.. necting bar and must. be held in an upright relaticnship with respect to the bumper of each ve, hicle so that a lever action of the connecting bar I3 may be eiective. The upper and lower l.laws of each clamp are connected together, in use by a chain bolt arrangement, the chain engaging the upper clamp jaw and the chain bolt being secured to the lower clamp jaw.

The bumper clamps Il and i2 are both sub `iected to the same general stress in straight pull ing and, consequently, are of the same basic con struction. However, the force necessary to secure adequate control over the rear vehicle, Dar-tiens larly in turning, makes it desirable to provide extra strength and rigidity in the rear clamp jaw I4. Such strength and rigidity is accom.. plished to a large extent by the design and relationship of the various component parts, which in themselves are simple and easily fabricated.

As shown in Fig. 4, the rear clamp jaw is made up of a vjaw plate 2|, a connecting plate 22, and an L-shaped stiiening plate 23. The jaw plate 2| is formed from :dat stock into a generally U- shape, one leg of which has a jaw .portion 24 suit ably curved to t over and grip the edge of an automobile bumper. Another 'leg 2-5 of the jaw plate is recessed to provide an opening Z6 adapted to receive the chain bolt 21 which is interlocked with a chain .28. In alignment with the opening 2t is an opening 29 in an opposed leg 30 of the jaw plate through which the chain bolt '2 7 extends and in which it is held by a .nut 3.2 and accompanying lock washer 3l. The jaw plate ,2| is provided with .another opening 33 through which the connecting bar I3 extends in the assembly.

The `connctting plate i22 is also termed :from nat stock into a generally shane having :a :dat weber base portionY 34 and opposed wings or Alegs 36. The size and shape of the plate 22 are made complementary to the inside of the jaw plate 2 I. The wings 36 of the connecting plate have aligned openings 31 therein for receiving a bolt, rivet, or the like, extending laterally of the clamp jaw. Stiifening plate 23 is L-shaped and made from a flat stock plate having one leg 36 curved back upon itself to afford rigidity and to provide a lip 35 which, in the assembly, extends along the jaw portion 24, in spaced relationship thereto.

In assembling the rear clamp jaw I4 the connecting plate 22 is placed within the jaw plate 2l with the wings 36 approximately equidistantly spaced from opposite sides of the opening 33. The complementary fit of the plates 2l and 22 causes the edges of wings 36 and web portion 34 to fit snugly within the jaw plate. Stiifening plate 23 with its turned end 33 extending outwardly is then placed against the web portion 34 of the connecting plate. The plates are then rigidly secured together as by welded seams 39, along all of their adjacent surfaces.

The forward clamp jaw i6 is similar to the rear clamp jaw in that it has a jaw plate 4I, connecting plate 42, and a Z-shaped stiffening plate 43. The jaw plate 4I has a recess 44 therein for receiving the connecting bar I3, an opening Mi in the mid-portion thereof for receiving the chain bolt 21, and a jaw portion 21 for gripping the bumper of the forward vehicle. The connecting plate 42 is substantially U-shaped and has a fiat web or `base portion d8 and opposed wings or legs 49; the wings having aligned openings 5I therein. The stiffening plate i3 is Z-shaped in vertical cross section and includes a stiifening flange portion 52 integrally formed as one leg thereof and terminating in an angularly disposed lip 50, and spaced flanges 53 to provide an opening or slot 54 for receiving the chain bolt 21. The plates 4I, l2 and 43 of the forward clamp jaw I6 are assembled and secured together by welded seams, such as 55, in a manner similar to that of the rear clamp jaw I4.

While the forward and rear clamp jaws are of the same basic design, it will be noted that in the preferred embodiment of the invention the rear clamp jaw Id is of sturdier and more rigid construction tl'ian is the forward jaw i6. This is done to provide wider lateral gripping action and greater strength and leverage for effecting control of the towed vehicle, particularly in turning corners and the like.

The forward and rear clamps II and I2 connected together by connecting bar i3.

are The bar I3 has a universal joint 56 intermediate its r ends which divides the bar into two sections 51 and 58. The universal joint 56 utilized in the preferred embodiment of the invention is of simple but sturdy design. It comprises a yoke 53 of'general U-shape having a web portion 6I and wings 52 in spaced and opposed relationship. In the mid-portion of the web I is an opening 53 which rotatably receives a cylindrical end portion e4 on the forward end of the `bar section 53 which is integral with and projects longitudinally from the bar section 52. A collar 55 is welded onto the end of the cylindrical end portion 64 of the bar section to secure that bar section to the yoke, while preserving the rotatable relationship between those connected parts. This rotational relationship of the bar sections eliminates torsional stress which would otherwise result from the relative tilting of connected vehicles during use of the tow bar.

The connecting bar section 51 is pivotally secured to the yoke 59 by a pin or rivet 61 which extends through aligned openings 68 and 69 in both the yoke and one end of the bar section. This pivotal connection constitutes a point of control of the rear vehicle as for effecting turning and the like. As the forward vehicle turns, the bar section 51 is moved out of lateral alignment with bar section 58, the continued pull of the forward vehicle forces the rear vehicle to turn and thereby effects return of the rear bar section 5S back into alignment with the forward bar section.

The position of the universal joint with respect to the length of the connecting bar I3 has been found to be important in obtaining more effective control of the towed vehicle. Although practical considerations dictate that the connecting bar shall be as short as possible, the rear bar section 58 must be of substantial length in order to provide leverage for forcing the rear vehicle to turn with practically instantaneous response to the controlling movements of the towing vehicle. It is with the foregoing considerations in mind that I have placed the universal joint in the forward half of the bar I3. In this position, the action of the bar, when the forward vehicle is turning, is such that considerable leverage is exerted on the rear vehicle, because of the length of bar portion 53.

The connecting bar I3 is pivotally secured to both the front clamp jaw and the rear clamp jaw. In each instance, the axis of the pivotal connection of an end of the bar to one of the clamp jaws is horizontal when the tow bar is in use, so that fiexibility in the plane steering forces is avoided, while the bar permits relative movements of the vehicles caused by unevenness of roads over which they pass. As shown in Figs. 2 and 3, the rear bar section 53 extends through opening 33 of the rear clamp jaw I4 and between the wings 36 of the connecting plate. An opening 1I in the bar section 58 is aligned between openings 31 in the plate; the bar section being secured in place by a pin 12. The forward bar section 51 is similarly secured to the forward clamp jaw I5 by pin 13 extending through opening 1li in the bar section and aligned openings 5I in the connecting plate 42. These pivotal connections of the bar I3 to the front and rear clamps Il and I2 eliminate stress on the bar when the forward and rear vehicles are displaced vertically with respect to each other.

In the disclosed structure, front and rear clamps II and I2 are secured to the vehicle bumpers 3 and 9 by chain bolt 21 and chain 28 connecting the upper and lower clamp jaws of each clamp. In securing the rear clamp Il, as shown in Fig. 2, upper clamp jaw I5 is hooked over the upper edge of the vehicle bumper 9 and the jaw plate 2| of the lower clamp jaw is placed under the lower edge of the bumper. Chain bolt 21 is then placed through'openings 26 and 29 of jaw Iii and the washer 3| and the nut 32 engaged thereon. 'Ihe appropriate link of chain 28 giving the tightest fit is placed in slot 25, such link being held in place by the seating of the next upper link. The nut 32 of the chain bolt is then tightened until a rigid, non-slip engagement of the clamp to the bumper is effected. The front clamp II is similarly secured to the bumper 8 of the front vehicle. This arrangement of attaching the clamps permits instant and efficient securement of the tow bar to the vehicle bumper.

While I have illustrated a preferred embodi-- ment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not Wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A clamp jaw comprising a first part having a clamping fia-nge, a second part in the shape of a U having legs each provided with a hole adjacent one side of the leg, said flange being disposed outward of the base of the U-shaped part and said first part engaging the edge of the side of each leg thereof away from the side to which the hole is adjacent, the rst part also having a slotted region engaging the end edges of the U-shaped part, and a Z-shaped part having the face of the web thereof in engagement with the outer face of the base of the U-shaped part, and the face of a leg of the Z-shaped part in engagement with the rst part, the three aforementioned parts being secured to one another.

2. The clamp jaw specified in claim 1, the said one leg of the Z-shaped part having a lip arranged in spaced facing relation to the clamping fiange, the first part and the Z-shaped part being wider than the U-shaped part so as to extend outwardly of the legs thereof.

3. A clamp jaw comprising a first U-shaped part having a long leg provided with a clamping fiange at its free end, a short leg provided with a slot at its free end, and a base provided with an opening adjacent the short leg; a second U- shaped part having a hole in each leg near the free end and one side edge thereof, said flange being disposed outward of the base of tne second part and the long leg of the first part engaging the edge of the side of each leg of the second part away from the side to which the hole is adjacent, and said short leg provided with the slot engaging the side edges of the econd part, an L-shaped part, the second U-shaped part lying Within the first U-shaped part with the planes of the legs of the Us transverse to one another, the holes in the legs of the second part being adjacent the short leg of the first part and the opening in the base thereof, and the edges of the base of the second part engaging the inner face of the long leg of the rst part and the free end of the inner face of the short leg of the first part in bridging relation to the slot in the said short leg, the outer face of one leg of the L-shaped part engaging the outer face of the base of the second part, the

outer face of the other leg of the L-shaped part engaging the inner face of the long leg of the iirst part, and the three aforementioned parts being secured together.

4. The clamp jaw specified in claim 3, each leg of the second part being longer at the region containing the hole than at the remainder of the leg and being rounded at the free edge beyond the hole, the region of the base of the first part containing the opening being correspondingly rounded to fit the rounded free edges on the legs of the second part.

5. A clamp jaw comprising a first part having a clamping flange at -one end and spaced projections at the other end defining a slot, second part in the shape of a U, and a third part in the shape of a Z, one face of the first part engaging the U-shaped part at one base edge and at one side edge of each leg, each of said legs having an opening adjacent the opposite side edge and the free end, one face of each projection on the first part engaging the end edge of one leg of the U-shaped part adjacent the said one side, the Z-shaped part having the outer face of one leg in engagement with the said one face of the first part and the outer face of the web in engagement with the outer face of the base of the U-shaped part, the three aforementioned parts being secured together.

6. The clamp jaw specified in claim 5, the leg of the Z-shaped part engaging the base of the U-shaped part comprising spaced flanges engaging the side edges ofthe U-shaped part to which the said holes are adjacent.

7. The clamp jaw specified in claim 6, the spaced fianges of the Z-shaped part extending along the sid-e edges of the legs of the U-shaped part as far as the openings in the legs, each leg of the U-shaped part being longer at the region containing the hole than at the remainder of the leg and being rounded at the free edge beyond the hole.

ARTHUR. R. GROSS.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,730,077 Isachsen Oct. 1, 1929 2,306,388 Johnson et al Dec. 29, 1942 2,338,934 Gross Jan. 11, 1944 2,444,086 Baker, Jr June 29, 1948 2,446,218 Dunlap Aug. 3, 1948 2,472,325 Williams June 7, 1949 2,488,415 Klein Nov. 15, 1949 

